Methods for Tissue Culture of Dendrobium officinale and Selection of Cultivation Sites and Facilities
Selection of Tissue Culture, Cultivation Sites and Facilities for Dendrobium officinale
I. Tissue Culture Techniques for Dendrobium officinale
The seeds of Dendrobium officinale are affected by various factors during germination. If these factors cannot be effectively controlled, they will change the germination rate of Dendrobium officinale seeds, thereby affecting the yield and quality of Dendrobium officinale. After studying the relationship between seed age and germination, some scholars found that when using tissue culture techniques for germination, seeds with a seed age of 2-6 months were selected for separate cultivation. Among them, seeds with greater seed age showed obvious advantages in cultivation operations: the greater the seed age, the shorter the time required for germination and the higher the germination rate. It can be seen that when carrying out tissue culture, seeds with greater seed age should be preferentially selected for cultivation. In addition, adding appropriate NAA, IAA and IBA hormones to the culture medium promotes root growth in test-tube seedling cultivation. Therefore, during tissue culture, in order to increase the root growth rate of seedlings, hormones can be appropriately added to the culture medium according to actual cultivation conditions, thereby achieving the purpose of increasing income and yield.
II. Cultivation and Management Techniques for Dendrobium officinale
1. Hardening and Removal from Bottles
Hardening refers to the entire process of transplanting cultured test-tube seedlings into a hardening room and allowing them to grow there for about 3 weeks, during which the test-tube seedlings adapt to the natural environment. After a period of cultivation, once the leaves of the seedlings become dark green and the root system has grown to a certain length, they can be removed from the bottles for planting.
After the test-tube seedlings have been cultivated in the hardening room for 2-3 weeks, observe the growth condition of the seedlings. Only when the multiplication generation is within 10 generations, the seedlings have grown to 3 cm, have grown more than 3 nodes of fleshy stems, and the number of leaves has reached about 5 with normal color can they be removed from the bottles. In addition, there are certain requirements for the growth state of the root system: specifically, the root epidermis should be white with a hint of green, the root length should be more than 3 cm, and the number should be more than 5 roots, with no black root hairs or deformed roots.
The specific operation method for removing from bottles is as follows: in order to reduce damage to the seedlings caused by improper removal, the culture medium and seedlings need to be taken out together, and then the well-developed seedlings should be handled separately from contaminated seedlings and seedlings with fewer roots. After normal seedlings are taken out, they first need to be washed with tap water to remove the agar on the surface, so as to avoid root rot caused by residual agar. After the agar on the surface is cleaned, rinse again with clean water. For seedlings with poor root development, they need to be soaked in rooting powder, and only after the root system is fully developed can the next stage of planting be carried out. For contaminated seedlings, carbendazim should be used. After sterilization treatment, they should be planted separately to avoid adverse effects on the growth of other healthy seedlings due to incomplete sterilization.
2. Selection of Cultivation Sites and Facilities In order to ensure the yield and quality of Dendrobium officinale, it is necessary to first study the biological characteristics of Dendrobium officinale and then select an appropriate planting area. Generally speaking, areas where wild Dendrobium officinale is distributed are more suitable for its cultivation. If there is no wild Dendrobium officinale in the planting area, then conditions such as temperature, humidity, light and ventilation need to be comprehensively considered to determine the final planting area. If the conditions of the planting area do not match those required for the growth of Dendrobium officinale, artificial intervention can be adopted to provide a suitable growing environment. Generally speaking, a greenhouse needs to be built, and ventilation and shading work should be done well. The scale of greenhouse construction needs to be determined according to the actual number of plants to be planted, ensuring that the spacing between plants is reasonably set so as to achieve good ventilation effects and growth requirements. In addition, shade nets should be set on the top of the greenhouse, ventilation openings should be set around the perimeter, and the bottom should be well sealed, while insect-proof nets should also be set to prevent mosquitoes and insects from entering and affecting crop growth.
3. Substrate Selection
In the cultivation techniques for Dendrobium officinale, the selection of substrate is directly related to the survival rate, growth condition, reproduction degree and final yield of Dendrobium officinale. Therefore, sufficient attention should be paid to substrate selection. After years of development, many substrate types have been obtained, and in actual cultivation work an appropriate substrate can be selected according to specific conditions. After comparative analysis of the cultivation conditions of various substrates, it can be found that when using a 5 cm limestone gravel drainage layer + 8 cm sawdust + 2 cm live moss as the substrate, Dendrobium officinale has the best growth and the highest yield.
4. Transplanting Time and Method
Because the planting of Dendrobium officinale has relatively high temperature requirements, the choice of planting time is particularly important. Too high or too low a temperature will affect the growth state of Dendrobium officinale. Generally speaking, for southern regions, planting can be carried out except during the extremely cold weather of January-February and the hotter weather of July-August, but the best planting time is between April and May.
The specific transplanting method is to dig a shallow hole 2-3 cm deep in the substrate, gently place the roots of seedlings that have undergone hardening and bottle removal treatment into the hole, taking special care that the root system is not easy to bend, and finally cover with substrate. In order to facilitate subsequent planting management work, normally developed seedlings, contaminated seedlings and few-root seedlings can be planted in separate zones.
5. Cultivation Management
Light. Zheng Yongping et al. believe that controlling light intensity within 30,000 lx is most suitable for the growth of tissue-cultured seedlings of Dendrobium officinale; temperature and humidity. Tissue-cultured seedlings of Dendrobium officinale grow in cool, moist and well-ventilated places, and their suitable growth temperature is 20-30°C. When the temperature is high in summer, the greenhouse must be ventilated and heat-dissipated, and spraying should be carried out at the same time to cool down and maintain moisture; when the temperature is low in winter, heating can be used to control it at around 10°C. Within 1 week after transplanting, the air humidity should preferably be maintained at around 90%, and after 1 week the air humidity can be maintained at 70%-80%.
III. Harvesting of Dendrobium officinale
Dendrobium officinale can be harvested after 2-3 years of planting. The suitable harvest period is from after "Lidong" to before "Qingming", when Dendrobium has stopped growing and the stems are firm, plump and dry. In order to sustainably utilize the limited resources of Dendrobium officinale, the method of "remove three, keep two" should generally be adopted, that is, harvest stems of Dendrobium officinale that are 3 years old and above, and leave those under 3 years old for growth and reproduction. After harvesting, attention should be paid to promptly spraying protective fungicides to prevent the occurrence of diseases.
Judging from the current development situation of Dendrobium officinale cultivation, shortening the growth cycle and expanding reproduction are still key contents. Although this can improve the yield and efficiency of Dendrobium officinale production to a certain extent, quality cannot be guaranteed, and this rapid cultivation method makes it difficult to ensure the medicinal value of Dendrobium officinale. In view of the above problems, it is recommended that future research on cultivation techniques pay more attention to quality control and strengthen research on the biological characteristics of Dendrobium officinale, so as to provide it with a more suitable growing environment.